Posts Tagged ‘Model A frame’

Below are a few sample drawing of the chassis / frame using the 1984 – 87 C4 Corvette suspension parts. Click on the “Chassis Plan Page” link below for a complete set of measured drawings and pictures.

Building a hot rod, street rod, custom car, or rat rod is not an easy project to undertake. Using the suspension from the 1986 Corvette Indy Pace car convertible had its challenges. At the time so little information could be found for this type of chassis / frame design. While undertaking the build, I measured the original C4 Corvette cross member and rear end and recorded everything as I worked on the build. It was difficult, but a very rewarding challenge.
Purchasing the wrecked Corvette on eBay for my hot rod build was a very affordable method of obtaining the major components for the 1929 Ford roadster hot rod. In the end, I kept all of the suspension parts, motor, transmission, steering column, brake booster, and many other small parts. Everything else was sold, including the much stripped down wrecked Corvette shell. Very little was thrown away. The wheeling and dealing resulted in a tidy profit. The initial cost of the 1986 Corvette was recovered and a very healthy amount left over for the purchase of tools and parts required for the hot rod build. Who said that building a hot rod is expensive?
After giving this a considerable amount of thought, I decided to finish the measured drawing of the chassis / frame on ACAD and share them with other hot rod builders. These plans would also be useful to other street rod, custom car, rat rod, or hot rod builders and adapting the design to your unique build.

If you feel that this information was useful please, consider making a donation. It was a huge effort to create these drawings.

Below is a short video of the plans and pictures of various parts of the chassis / frame explaining a few of the build details.

Before any suspension is removed from the Corvette, it is a very good idea to record how everything is mounted to the car. Now with digital cameras, I always take pictures of any demolition, modification, or repair for future reference. In the case of the Corvette suspension, I recorded on paper the dimensions, angles, and location of all parts mounted to the frame of the car. I did not have a digital camera then. You might think you will remember every detail, but I can guarantee that you will forget something important. It is said that a picture or detailed sketch is worth a thousand words. I believe this from years of experience.

The first step was to remove the motor and transmission from the car. Now the front suspension can be removed very easily. No cutting tools are required for the removal. The front cross member is bolted to the main Corvette frame. The cross member also has the mounting for the motor mounts. This is so well designed, that all of the front suspension components are attached to the front cross member with the exception of the upper shock mounts. I will come out of the car as a complete unit.

It is important not to discard any items from the Corvette. Every single part removed can be sold. This is what I did. I listed many parts on eBay and sold many items locally. This eventually paid for the car and made me even more money. I managed to pay for the engine hoist, engine stand, and a new Millar Mig welding machine from the proceeds of this car. I even put some money in the bank for my next street rod part purchases. Don’t forget, I still have the Corvette suspension, engine, transmission, and many other parts needed to build my street rod. I never thought building a street rod was so profitable.

Next I removed the rear suspension. Again, everything came out without any difficulty. Make sure you keep the bolts. The bolts are all hardened bolts and might be required to mount the suspension in the new Model “A” chassis. I even removed all of the emergency brake cables, and aluminum brake line splitters.

The front and back sway bars and mounts should to be removed and stored. One of my main goals in the design of the new Model “A” Ford chassis was to use as many Corvette parts as possible in my street rod. This makes the long term maintenance of your street rod very simple. Corvette parts will always be available whereas custom made parts will be hard to replace when items break or wear out. Some of the custom parts built today might not be available in the future depending who originally made them.

I placed the front and back suspension units on a skid and wheeled them off to my shop. Now I needed to decide on the details of the chassis design. I felt that for my first street rod, I would not be too radical in my design. In some sense, I did select something out of the ordinary by using C4 Corvette suspension on a 1931 Ford Coupe. This will complicate the design enough and slow down the building process when compared to using traditional parts in a street rod.

C4 Corvette rear suspension as removed from the 1986 Corvette Indy Pace car convertible. As few parts need to be replaced due to the accident the car was in.

I decided to use the same wheel base of 103 ½” as the original Model “A” Ford for a 1928 to 1931 frame. The mounting of the rear suspension required a narrower frame width. It was like the C4 Corvette design engineers considered the Model “A” Ford in their original design applications. The width of the rear frame rails would be narrow enough to fit between the rear body frame rails. I would only need to make a slight modification to the body frame rails to facilitate the new suspension and chassis.

C4 Corvette front suspension as removed from the 1986 Corvette Indy Pace car convertible. Everything will be removed from the front crossmember. I will use the front crossmember for the basis of my design and measure everything on it.

I measured the mounting distance between the upper control arms on the Corvette cross member. It was slightly wider than the original Model “A” Ford frame. It is important not to change any part of the original design of the suspension of the Corvette. Any changes will affect the eventual performance in handling and ride of the street rod. In some street rod applications, the entire Corvette front cross member can be used as is. It is not possible for the Model “A” Ford. I suppose some car builders would say sure no problem, use it as is. I feel the front of the car would look very ugly and be poorly designed and this option was not for me. It would be similar to builder using an original Mustang II suspension with the large coil springs. In a small car like a Model “A” Ford, this will not look good. Again maybe in larger street rods with the front ends closed in more would this be okay.

C4 Corvette front cross member stripped down and ready to have measurements taken from. The new street rod cross member will not look anything like this.

Now I had a basic design concept for the new chassis in place. The original wheel base would be adequate, and a new width at the center lines of the front and rear suspension was determined. Now, I needed to buy the steel for the new chassis.

Fortunately, in our town, we have a steel supplier. I purchased 2” x 4”, 0.1” wall thickness rectangular tubing. Before my purchase, I completed rough sketch of the new Model “A” Ford chassis. From my sketch, I calculated how much material was required for the main frame rails, rear of the frame, and the new front cross member. At the steel supplier, I had them cut two sections of the same length of tubing for my new chassis. We loaded this into my trailer and headed back home to my shop.

The next phase of the project is to complete a mock up of the new chassis with everything only tack welded.

More to come soon, including pictures of the design process. Make sure you book mark this site and come back for weekly updates.